1. Field of the Invention
The present invention relates to a disc changer, and a method of detecting a mode thereof, and a method of selecting a disc ejection. The disc changer is capable of storing optical disc recording media including CDs (Compact Discs) and DVDs (Digital Versatile Discs) and automatically recording and reproducing a selected recording medium of the stored media. Also, the disc changer is of a tray-transport type having a plurality of subtrays for transporting a recording medium set thereon.
2. Related Art
Disc changer is capable of storing a plurality of optical disc recording media including CDs, and selecting one of the stored optical disc recording media to perform recording and reproducing of the selected one. This kind of disc changers are widely used and provided in various forms. However, disc changer need many operations to accommodate a plurality of discs and select a disc out of them for recording and reproducing the selected one, and to replace the selected disc with another one, which inevitably increases the number of motors the disc changer has. Conversely, when a structure is adopted such that the number of the motors is limited, the operations are performed selectively and as such, various kinds of sensors and a mechanism for switching powers are required.
For example, “Rotation transmission change-over mechanism” according to JP-A-2002-243015 is arranged so that a single motor carries out both eject operation (operation of transporting a carriage or a subtray to its disc replacement position) and play operation (operation of transporting the carriage to its disc reproduction position), and a driving path is switched by a plunger. The mechanism includes: a plunger with a lever for transferring a rotation gear toward the direction of the rotational axis; carriages superposed one on another and installed so that the eject operation or play operation is enabled when the operation is selected; a driving means for the eject operation and the play operation; an operation switching means for switching operational transmission to a selected operation of the eject operation and the play operation; and an operation-transmitting means for carrying out eject operation or play operation, wherein one of a first gear or a second gear is connected to the operation switching system and the other gear is connected to the operation-transmitting system. Then, the rotation gear is adjusted in its rotating position and engaged or removed so that it meshes with one of first and second switching gears.
However, use of the plunger causes a noise with each switching, raises the cost of components, and increases the power consumption, which poses heat-producing and fire hazards. Also, it increases electrical lines and circuit boards and inevitably enlarges size of the device. In addition, there is an apprehension that a magnetic field generated by the plunger influences other components.
Incidentally, in a tray-transport type disc changer the following main operations are generally carried out in order to select, record, and reproduce one of disc-type recording media stored therein.
(1) Operation of transporting a tray in a disc replacement position (disc-removing position) to a disc waiting position.
(2) Operation of vertically moving a traverse unit to the position where a tray with a selected disc placed thereon is located.
(3) Operation of transporting the tray with the selected disc placed thereon to a disc reproduction position.
(4) Operation of clamping, recording and reproducing the disc.
(5) Operation of transporting the tray located in the disc reproduction position to the disc waiting position.
(6) Operation of selecting a tray located in the disc waiting position and transporting the tray to the disc replacement position (disc-removing position).
In a disc changer, it is required to grasp which operation step the selected given disc is in and then proceed to a next operation step. The operation may be stopped in the case where a trouble occurs in the operations described in (1) to (6) under some influence, or in midstream. Further, various operations are performed in the case where it is required to bring out a disc during the operation of reproducing the disc, and other cases. Furthermore, various troubles may occur and as such, it is required to check a current operation correctly because, otherwise it becomes impossible to continue subsequent operations. Also, even in a process of reproducing a disc, it is required to perform the operation of ejecting a disc in the waiting position to replace it with another one.
“Disc reproducing device with a disc changer” according to JP-A-10-134474 is arranged so that a single motor is used as a driving source to carry out both the operation of transferring a disc tray for replacement of the disc and the operation of transferring a disc tray for disc loading, and the device is simplified in a power-transmission switching mechanism. However, the disc reproducing device has eight microswitches to identify the operations. Use of the contact-type microswitches produces variations in form and size in contact areas, thereby reducing the detection accuracy. The disc reproducing device with the disc changer uses three subtrays and eight lever switches. In the case where the number of subtrays is increased, the number of detecting operations is increased and therefore it is required to increase the number of microswitches.
Further, a switch lever portion can contact another component to become deformed. In such case, the switch can not function whatsoever. Therefore, the more the switches, the load on the microcomputer becomes heavier. Consequently, the microcomputer used to cope with such situation becomes more expensive. In addition, an increase of the number of switches increases the numbers of wiring materials and boards, which makes the device more complicated. As a result, the disc changer becomes more complex and more expensive as a whole.
Conventional disc changers have problems as described above. The problems to be solved by the invention are these problems. It is an object of the invention to provide a disc changer, which is capable of working without any malfunctions in spite of a reduced number of switches and which has a simple structure and can be manufactured at low cost, a method of detecting a mode thereof, and a method of selecting a disc ejection.